Passive seat belt retractor assembly

Abstract

A seat belt retractor assembly particularly adapted for mounting in a motor vehicle door as part of a passive belt system. The retractor includes both an inertia sensitive actuator and a tension relief or "comfort" features. The retractor further includes an operating system which renders the inertia sensitive actuator and comfort mechanism inoperative while the vehicle door is being opened or closed to allow the belt webbing to be freely withdrawn and retracted onto the retractor spool during such door movement. The operating system is actuated by an electrical solenoid. The force output and size of the electrical solenoid are minimized by employing a system which uses rotation of the retractor spool which "cocks" a latch plate member against spring tension and using the solenoid only to release the release plate when necessary.

We claim: 
     
       1. A seat belt retractor for providing motor vehicle occupant protection comprising: a rotatable spool for storing seat belt webbing,   a rewind spring exerting a retraction force on said webbing,   comfort means for releasing tension on said webbing exerted by said rewind spring, and   means for cancelling said comfort means including operating means movable between a first position for acting upon and cancelling said comfort means and a second position enabling normal operation of said comfort means, biasing means urging said operating means toward said first position, actuation means for moving said operating means from said first to said second position upon rotation of said spool, release means for maintaining said operating means in said second position, and latch means for acting on said release means to release said operating means to enable said operating means to return to said first position.   
     
     
       2. A seat belt retractor according to claim 1 wherein said operating means comprises a rotatable release plate movable between said first and second positions. 
     
     
       3. A seat belt retractor according to claim 2 wherein said biasing means comprises a coil spring affixed to a frame member of said retractor and said release plate. 
     
     
       4. A seat belt retractor according to claim 2 wherein said comfort means comprises a stylus engagable with grooves of a cam plate and said release plate is engagable with said stylus to move said stylus out of engagement with said grooves when said operating means is in said first position. 
     
     
       5. A seat belt retractor according to claim 2 wherein said actuation means comprises a pawl link pivotally connected to said release plate and engagable with teeth rotatable with said spool. 
     
     
       6. A seat belt retractor according to claim 2 wherein said release means comprises a lock pawl rotatable to engage said release plate to maintain said release plate in said second position and movable to disengage said release plate. 
     
     
       7. A seat belt retractor according to claim 1, further comprising inertia sensitive means for inhibiting extension of said webbing from said retractor when said retractor is subjected to a deceleration load above a predetermined level, and an electric solenoid which acts on said latch means and said inertia sensitive means to cancel both said inertia sensitive means and said comfort means. PG,17 
     
     
       8. A seat belt retractor for providing motor vehicle occupant protection comprising: a frame for mounting to a motor vehicle structure,   a spool for storing seat belt webbing carried for rotation by said frame,   a rewind spring exerting a torsional loading on said spool for exerting a retraction force on said webbing,   inertia sensitive means for preventing rotation of said spool when said retractor is subjected to a deceleration load above a predetermined level, said inertia sensitive means including a locking bar engagable with said spool,   comfort means for relieving tension on said webbing exerted by said rewind spring, and   retractor operating means for cancelling said inertia sensitive means to prevent engagement between said locking bar and said spool and for cancelling said comfort means to prevent said comfort means from relieving tension on said webbing, said retractor operating means including a release plate mounted for rotation to said frame, spring means coupled to said release plate and said frame, actuation means for rotating said release plate from a first to a second rotated position wherein said spring means biases said release plate toward said first position, cancelling means carried by said release plate for cancelling said comfort mechanism when said release plate is in said first position, release means for latching said release plate in said second position, latch means actuated by an electric solenoid for unlatching said release means thereby causing said release plate to move to said first position thereby cancelling said comfort means, said electric solenoid further rendering said inertia sensitive means inoperative.   
     
     
       9. A seat belt retractor according to claim 8 wherein said comfort means comprises a stylus carried by said retractor frame engagable with grooves formed on a comfort cam rotatable with said spool, and said cancelling means comprising a ramp surface engagable with said stylus when said release plate is in said first position to disengage said stylus from said grooves. 
     
     
       10. A seat belt retractor according to claim 9 wherein said actuation means includes a pawl link carried by said release plate having an arm engagable with teeth coupled to said spool for engaging with said teeth for moving said release plate from said first to said second position and said release means comprising a lock pawl having an engaging surface for latching said release plate in said second position through engagement with an abutment surface of said release plate and wherein said solenoid is coupled to said lock pawl. 
     
     
       11. A seat belt retractor according to claim 10 wherein said inertia sensitive means comprises a pendulum acting on said lock bar engagable with toothed sprockets of said spool and wherein said electric solenoid engages said lock bar to render said inertia sensitive means inoperative when energized. 
     
     
       12. A seat belt retractor for providing motor vehicle occupant protection comprising; a frame for mounting to a motor vehicle structure,   a spool for storing seat belt webbing carried for rotation by a spool shaft journaled to said frame,   a rewind spring exerting a torsional loading on said spool for exerting a retraction force on said webbing,   inertia sensitive means for preventing rotation of said spool when said retractor is subjected to a deceleration load above a predetermined level, said inertia sensitive means including a locking bar engagable with said spool,   a comfort mechanism including a cam plate rotatable with said spool, said cam plate forming grooves on a face surface thereof, and said comfort mechanism further including a stylus coupled to said frame and having a tip engaging said grooves for relieving tension on said webbing exerted by said rewind spring, said cam plate further forming teeth projecting from its periphery, and   a retractor operating mechanism for cancelling said inertia sensitive means to prevent engagement between said locking bar and said spool, and for cancelling said comfort mechanism to prevent said mechanism from relieving tension on said webbing, said retractor operating means including a release plate mounted for rotation about said spool shaft between a first and second rotated position and having a raised edge acting on said stylus when said release plate is in said first position to prevent engagement with said grooves, spring means coupled to said release plate and said frame for biasing said release plate toward said first position, a pawl link carried for pivoting movement by said release plate and having a finger engagable with said cam plate teeth to cause said release plate to move to said second position upon retraction of said webbing, a lock pawl for latching said latch plate in said second position, a blockout lever for engaging said locking bar to prevent engagement with said toothed sprocket, and for moving said lock pawl to disengage said release plate.   
     
     
       13. A seat belt retractor for providing motor vehicle occupant protection comprising: a rotatable spool for storing seat belt webbing,   a rewind spring exerting a retraction force on said webbing,   inertia sensitive means for inhibiting extension of said webbing from said retractor when said retractor is subjected to a deceleration load above a predetermined level,   comfort means for releasing tension on said webbing exerted by said rewind spring, and   comfort cancelling means for cancelling said comfort means movable between a first position cancelling said comfort means and a second position allowing said comfort means to release tension on said webbing including biasing means for urging said comfort cancelling means to said first position, actuation means for moving said comfort cancelling means to said second position, release means for maintaining said comfort cancelling means in said second position, and   drive means for acting on said inertia sensitive means to render said inertia sensitive means inoperative and for actuating said release means to cause said comfort cancelling means to move to said first position thereby cancelling said comfort means.